linux-kernel - Re: [PATCH -V6 RESEND 1/3] numa balancing: Migrate on fault among multiple bound nodes

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Message-ID: <87zh2ulyhc.fsf@yhuang-dev.intel.com>
Date:   Fri, 04 Dec 2020 17:19:43 +0800
From:   "Huang\, Ying" <ying.huang@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Rik van Riel <riel@...riel.com>,
        Johannes Weiner <hannes@...xchg.org>,
        "Matthew Wilcox \(Oracle\)" <willy@...radead.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>,
        David Rientjes <rientjes@...gle.com>, linux-api@...r.kernel.org
Subject: Re: [PATCH -V6 RESEND 1/3] numa balancing: Migrate on fault among multiple bound nodes

Peter Zijlstra <peterz@...radead.org> writes:

> On Wed, Dec 02, 2020 at 11:40:54AM +0000, Mel Gorman wrote:
>> On Wed, Dec 02, 2020 at 04:42:32PM +0800, Huang Ying wrote:
>> > Now, NUMA balancing can only optimize the page placement among the
>> > NUMA nodes if the default memory policy is used.  Because the memory
>> > policy specified explicitly should take precedence.  But this seems
>> > too strict in some situations.  For example, on a system with 4 NUMA
>> > nodes, if the memory of an application is bound to the node 0 and 1,
>> > NUMA balancing can potentially migrate the pages between the node 0
>> > and 1 to reduce cross-node accessing without breaking the explicit
>> > memory binding policy.
>> > 
>> 
>> Ok, I think this part is ok and while the test case is somewhat
>> superficial, it at least demonstrated that the NUMA balancing overhead
>> did not offset any potential benefit
>> 
>> Acked-by: Mel Gorman <mgorman@...e.de>
>
> Who do we expect to merge this, me through tip/sched/core or akpm ?

Hi, Peter,

Per my understanding, this is NUMA balancing related, so could go
through your tree.

BTW: I have just sent -V7 with some small changes per Mel's latest
comments.

Hi, Andrew,

Do you agree?

Best Regards,
Huang, Ying